A packaged electrode, which is made by packaging an electrode between a pair of separators, is known (see Patent Literature 1). In this packaged electrode, the separators are joined to each other at least at four corners thereof.
The separators are shaped like thin films, and easily curled up. Since a size of a battery for an electric vehicle and a hybrid vehicle in particular is much larger than a battery for a household appliance, handling is difficult, and it is more likely that separators are not only curled up, but also wrinkled. Therefore, separators are curled up or wrinkled when superimposing the separators on both sides of an electrode, thus making a joining operation for joining edges of the separators more complex. This inhibits improvement of efficiency in manufacturing a packaged electrode, and thus makes it impossible to enhance efficiency in manufacturing an entire battery.
Moreover, separators can be curled up or wrinkled not only when superimposing the separators on both sides of an electrode, but also thereafter. When the separators are curled up or wrinkled during operations thereafter, such as manufacturing of a battery by laminating a positive electrode and a negative electrode, complex operations for collecting the curling and wrinkles are necessary. In order to avoid this, it is preferred that separators are joined to each other not only in two lines that face each other in a planar view, but also in other line.